Pneumonia is the primary cause of child mortality worldwide. The global community is considering interventions to reduce pneumonia burden, including vaccines. Most attention is focused on bacterial vaccines. Influenza vaccine has not received attention due to lack of influenza burden data from high pneumonia endemic settings, and poor understanding of how influenza contributes, independently and with other pathogens, to childhood pneumonia burden. Data from Bangladesh indicate that influenza has a high incidence of over 10% per year among children < 5 years, and that among children who get influenza infection, 28% develop pneumonia, including severe pneumonia. Influenza-infected children who develop pneumonia are significantly younger (< 2y) than those who do not. Due to the high influenza incidence, and the high proportion of influenza-infected children who develop pneumonia, influenza is a major contributor to childhood pneumonia, not only in Bangladesh, but likely throughout the pneumonia endemic tropical and sub-tropical belt. Although trials have been conducted to examine influenza vaccine impact on influenza, none have been conducted specifically to determine the effect on childhood pneumonia, particularly among those < 2 years who are at highest pneumonia risk. We propose to conduct such a trial.